Electron coupled magnetron oscillator



April 24, 1951 R. B. NELSON 2,549,846

ELECTRON COUPLED MAGNETRON OSCILLATOR Filed Oct. 51, 1946 Fig.2. 43 7 am 27 27 3/ J0 33 2a la 2 In ventor: Richard B. Nelson,

b #M LML Hi5 Attorney.

Patented Apr. 24, 1951 ELECTRON COUPLED MAGNETRON OSCILLATOR Richard B. Nelson, Schenectady, N. Y., assignor to General Electric Co New York mpany, a corporation of Application October 31, 1946, Serial No. 706,896

Claims.

This invention relates to magnetron oscillators and has for its object the provision of an oscillator which will maintain a stable oscillation condition of highly constant frequency in the presence of circuit conditions normally tending to disturb that condition.

As is well known in the art, it is highly desirable for many applications to have available a stable high frequency oscillatorwhich wil1 maintain its frequency at a substantially constant value in the presence of conditions, such as excessive loading, which might tend to cause complete stoppage of oscillations or fluctuation of the oscillation frequency. Magnetron type oscillators heretofore known have not been as'satisfactory as could be desired for such purposes because they show a tendency to stop oscillating or to fluctuate in frequency when such circuit conditions as the amount of output loading or the phase relations thereof are varied, or when an attempt is made to modulate the output energy for the purpose of transmitting intelligence. I have found that by connecting the magnetron anodes in certain hereinafter described circuit arrangements, and especially when such arrangements incorporate a magnetron tube having a particular shielded anode configuration, hereinafter to be described in greater detail, it is possible to provide a magnetron oscillator which is measurably improved in these respects.

Briefly stated the object of the invention is accomplished by use of a magnetron circuit in which one or more of the anodes active in the generation of oscillations are relatively decoupled mutually with respect to one or more other active anodes except for any coupling effect which might be attributed to the electronic coupling effect .of the space charge. The first mentioned of these anodes are connected in electrically energizing relationship to a substantially load-free tank circuit which forms a constant frequency circuit controlling and determining the frequency of the oscillator at all times. The other anodes may be similarly connected to a load circuit which is maintained in oscillation at the desired constant frequency by the action of the magnetron tube and theaforementioned tank circuit. The fact that the respective circuits are, by virtue of the uncoupled relation of the respective anodes, relatively uncoupled exlationship between the load circuit and the frequency determining circuit has not been possible because the magnetron tubes heretofore common in the art have been so constructed that all of the active electrodes or anodes thereof are relatively tightly coupled together. Under such circumstances, when the load conditions in a circuit associated with any one anode is changed, a corresponding loading effect is reflected into all other anod circuits thereby givingrise to a tendency to disturb the stability or oscillation frequency thereof or even to stop oscillation completely in the case of excessive overloads. With my improved oscillator not only is the possibility of instability or frequency fluctuation minimized but also it becomes relatively impossibleto stop the oscillation completely .due to excessive overload.

. The features of the invention desired to be protected are pointed out in the appended claims.

' The invention itself together with its further obcept for the loose coupling effect of the space charge prevents the load circuit from having any substantial effect in disturbing stability or the frequency of the oscillations in the tank circuit. Heretofore, such relatively uncoupled re.-

jects and advantages will best be understood from the following description taken in connection with the accompanying drawings in which Fig. 1 represents schematically a circuit illustrating certain broad aspects of the invention; Fig. 2 represents in schematic cross-section one view of an illustrative magnetron oscillator embodying the invention and employing a magnetron having an anode configuration which is particularly useful for the purposes of the invenq tion; Fig. 3 represents a cross-sectional view of Fig. 2 taken in a plane normal to that of Fig. 2 in the direction of the indicated arrows along the line 3-3; while Fig. 4 represents schematie cally a circuit illustrating the broader aspects of the inventive embodiment illustrated by Figures 2 and 3.

Referring now to the Fig. 1, an oscillator embodying the invention in its broader form is shown as including a multi-anode magnetron, which may be of any of the types common in the art, comprising for example, a plurality of anodes l through 6 spaced about a cathode 1 in operative relation to a rotating space charge formed about the cathode 1 when the magnetron is energized by unidirectional electric and magnetic fields in the manner well understood in the art. The construction indicated may be enclosed within an evacuated envelope indicated schematically by the dotted line 8. For the purposes of the invention one group of the anodes I through 6, such as the pair I and 2, may be connected to a suitable high-Q resonant tank circuit which may comprise, for example, a tuned 3 parallel wire transmission line comprising conductors 9 and it tuned by means of a sliding short H. In a similar manner the group comprising the anodes 3 through 6 may be connected to a suitable load or power output circuit which, for example, may be a parallel wire transmission line comprising the conductors l2 and [3 across which a suitable load circuit M is connected at a suitable point. The conductor i2 is connected directly to the anode l while the conductor 13 is connected directly to the anode 5. The anodes 3 and may be connected respectively to the anodes 5 and 4 by the strapping arrangements known in the art whereby the pairs 3 and 5, and 4 and E are respectively connected to the conductors i3 and i2 as indicated. It will be understood by those skilled in the art that oscillations may be generated in the respective circuits if a positive unidirectional voltage is imposed upon the anodes with respect to the cathode I in the presence of a unidirectional magnetic field having a direction perpendicular to that of the plane of the figure. The unidirectional voltage is indicated being supplied by a battery [5 and the wire connections shown. Any suitable means (not shown) may be employed to supply the magnetic field.

As will be obvious from the Fig. l the respective resonant and load circuits are relatively decou pled from each other by virtue of the absence of coupling means between the group of anodes of the pair l2 and the group comprising anodes 3 through 6. The effect is obtained simply by omitting any of the conventional coupling means which ordinarily connect the anodes i and 2 to the remaining anodes of the tube. For example, if the magnetron is of the conventional cavity anode type in which the multi-anodes are interconnected by a plurality of strapping means, such means may simply be omitted with respect to the anodes l and 2. The load and resonant circuits are thus effectively decoupled with respect to each other whereby the imposition of load upon the load circuit will have a minimum effect in reflecting load impedance into the resonant cirits oscillations will be stable and constant in frequency.

The resonant tank circuit will be excited into oscillation by the anodes l and '2 and because no power is extracted from it except for the small circuit losses and perhaps some power delivered to the electron stream in the space charge chamber of the magnetron, it will operate with high frequency voltage (with respect to the cathode) of considerable magnitude. The remaining anodes 3 through 6 connected to the load end of the oscillator will generally operate with substantially less high frequency voltage and extract power from the electron stream of the space charge. The foregoing behavior is in contrast to the conventional magnetron oscillator wherein all active anodes are coupled together so tightly that they operate with substantially the same high frequency voltage. Thus, when the loading is changed in the conventional case, the loading conditions of all anode circuits is changed and the high frequency voltages on all anodes are affected. For efficient operation, this requires in the conventional case a loading adjustment which is relatively critical, since the conventional oscillator must be loaded heavily 4 enough to deliver a useful output of power and yet not overloaded to the point Where it will stop oscillating. Also, the heavy loading necessary for efficiency reduces the Q of the tank circuit to the impairment of frequency stability. With the uncoupled arrangement of the present invention, oscillation is maintained by the unloaded resonant tank circuit, formed by the conductors 9 and iii, regardless of the magnitude of the load connected to the load output, formed by the conductors I2 and I3, since the load is not reflected into the tank circuit. Thereby it becomes in practical eifect, impossible to load the oscillator sufficiently to stop all oscillation. Moreover, since frequency stability is determined by the Q of the unloaded tank circuit and since that Q remains unchanged regardless of load conditions greater stability with respect to modulation as well as the load impedance results.

Referring now to Figs. 2 and 3, the oscillator there shown includes a magnetron discharge tube having an anode arrangement which is particularly useful in effecting the desired decoupling between load and tank circuits. It comprises a magnetron discharge tube It which may be identical with that tube shown, described and claimed in my co-pending application Serial No. 700,939 filed October 3, 1946 and particularly in Figs. 3 and 4 of the drawing of that application. Such a tube may comprise an hermetically sealed envelope having a generally cylindrical wall I! preferably of thin steel tubing within which there are mounted a pair of magnetron anodes l8 and it active with respect to high frequency voltages as will be explained more fully hereinafter, electrostatic shielding means between anodes i8 and it such as a pair of anodes 2E! and 2| neutral with respect to high frequency voltages, a thermionic cathode 22, and a pair of magnetic pole pieces 23 and 24. The anodes l8, I9, 263 and 2| are provided with juxtaposed cylindrical faces defining a generally cylindrical chamber about and concentric with the axis of the cathode 22. The magnetic pole pieces 23 and 24 are so arranged as to establish, when suitably energized, a magnetic field (indicated by arrow H) parallel with the axis of the cathode within the cylindrical space defined by the anode faces. As will be well understood by those skilled in the art to which the invention pertains, the imposition of a relatively high positive potential on the anodeswith respect to the cathode will, in the presence of a sufiicient magnetic field, establish a rotating electron space charge in the chamber defined by the anode faces.

The shielding means exemplified by anodes 20 and 25 may be constructed in any equivalent form such that effective shielding action between active anodes I8 and I9 (and thereby between the here.- inafter described resonant and load circuits associated with the respective active anodes) is maintained. To that end, they will be such as will preclude the existence of any substantial high frequency electromagnetic field between the cathode 22 and the shielding means. The latter effect may best be obtained by insuring that the shielding means are connected to the cathode through low impedance paths e. g. in the illustrated embodiment, anodes 2t and El are connected to the wall I! by very low impedance paths. For the same reason and for the further purpose of minimizing radiation losses from the external cathode leads, the leads connecting cathode 22 to the wall H art preferably of minimum imped- 7 The magnetic pole pieces 23 and as may be an In order to prevent or to minimize the migrae tion to the seal region of electrons escaping from the electronically active regions between the anodes and consequent destruction of the seals, there may be provided a pair of annular suppressor disks 25 and 26 extending aroundthe periphery of the envelope. The disks may be mounted on insulating bushings 2'! of quartz or like material. The bushings in turn may be mounted by suitable means, such as nut and bolt structures, on a pair of annular metallic rings 28 and 29 extending around the periphery of the envelope and being brazed or otherwise rigidly secured thereto. The cathode 22 may be energized for thermionic emission by any suitable means (not shown) known in the art.

The end of the wall i1 may be closed by hermetic seals comprising the vitreous seal members 36 and 35 of glass or like dielectric material bonded to the annular metallic collars 32 and 33 and the cylindrical members 34 and 35 supporting the anodes i5 and I8 respectively.

As a means for maintaining constant oscillating frequency in the oscillator at predeterminable tunable value, there maybe provided at one end of the electrical discharge device a tunable high Q resonant tank circuit such as the coaxial transmission line comprising the inner conductor 36, outer conductor 31 and an annular slideable shortcircuiting member 38 adapted to slide conductively on the inner conductor in conductive contact with the outer conductor. This circuit will be adapted to operate free of load in order that its stability and frequency may not be disturbed by any change in oscillator load impedance or other conditions. As will be understood by those skilled in the art, the position of theannular tuning member 38 longitudinally of the line will determine the frequency of oscillation and the highest frequency which can be generated by the arrangement is determined by how close the tuning member 38 can be brought to the anodes of the device. As a means for deriving useful energy from the oscillator and transferring it to a suitable external load, there may be provided at the other end any suitable output connection such as the coaxial transmission line comprising the inner conductor 39 and the outer conductor as both of which are adapted 'to' be attached to some suitable external load (not shown).

Both inner and the outer conductors of both transmission lines are provided withberipherally positioned series of spring fingers 4i and 42 respectively. Fingers 42 resiliently engage the inner surfaceof the respective collars 32 and 33 in order to provide good electrical contact between the outer conductors and the wall I! of the envelope. The spring fingers 4! resiliently engage the inner surfaces of cylinders 34 and 3-5 to form good electrical contact with the cylinders and consequently'with the anodes I9 and IBQ In effect, the outer conductors 31 and 40 therefor' form conductive extensions of the wall I! thereby forming with the envelope an outer continuous conductor for the concentric lines. Inner conductors 36 and 39 eifectively form, in a similar manner, a continuous inner conductor for the line, broken only by the anode gap. It will be observed that these constructions provide convenient means whereby detachable external connections may be made between the discharge device and suitable concentric output lines to be employed therewith. The connections may be conveniently and rapidly detached should it be desired to replace the dis-- charge device 16 or to provide different external circuits therefor.

Itwill be understood that oscillations maybe generated in the arrangement shown whenever it is energized by suitable unidirectional electric potential imposed between the anodes [8, I9, 20 and 2i and the cathode 22 in the presence of a suitable unidirectional magnetic field directed perpendicularly to the electric field i. e. a magnetic field directed generally parallel to the axis of the cathode 22. The electric field may be provided by any suitable means such as the battery 43 having its negative terminal attached to the cathode 22 and its positive terminal to the wall H which is conductively connected to the anode l8 through the tuning means 38 and to anode l9 through the load circuit or a special conductive connection 44 provided for the purpose. The magnetic field represented by the arrow H may be provided in the manner already indicated.

In operation, the neutral anodes 20 and 2!,

being connected to the grounded wall II, will be at the same hi h frequency potential as the oathode. Under such conditions, anodes 20 and 2|, as already indicated, will serve as electrostatic shields to reduce the capacitative coupling between the anodes l8 and i9 and thereby prevent or at least minimize the reflection of loading impedance from the load circuit into the constant frequency tank circuit formed by conductors 36 and 3?. The tank circuit will thus operate substantially free of load and will therefore comprise a constant high Q circuit. It will be excited into oscillation by the anode l8 and because no power is extracted from it except for small circuit losses and perhaps some power delivered to the electron stream in the space charge chamber formed by the anodes, it will operate with high frequency voltage of considerable magnitude. Stable oscillation at constant frequency will be maintained under these conditions. The anode it connected to" the load end of the oscillator will generally operate with substantially less high frequency voltage and extract power from the electron stream. In the manner previously indicated, all of the foregoing behavior is in contrast to the conventional magnetron oscillator wherein all the active anodes are coupled together so tightly that they have substantially equal high frequency voltages. With this arrangement, oscillation is maintained by the unloaded tank circuit formed by conductors 36 and 3'! regardless of the magnitude of the load connected to the output formed by conductors 39 and 40 since the load is not reflected into the tank circuit. Moreover, since frequency stability is determined by the Q of the unloaded tank circuit and since that Q remains unchanged regardless of load conditions greater stability with respect to modulation as well as to load impedance results.

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7, psi m n ll strated by Fi s. 2 nd m o m: tedz n nyv specific. nu b r i no s to any specific form of the resonant and load circuits or to any specific construction of the shielding; eans: and t at it c ntemp a s q dl y magnetron arrangement in which one or more actiye magnetron anodes and a resonant frequency determining circuit associated therewith in electrically exciting relationship are decoupled by shielding means from one or more active anodes and a load circuit associated with the latter anodes in electrically exciting relationship. For example, there may be, in the place of anode 48, of Fig. 2-, two or more active anodes arranged to excite a parallel wire (lecher wire) line as the resonant circuit; while similar rearrangements of the load side may be e ected, The shield means in that case may be formed by any suitable. members occupying sectors corresponding to those occupied by neutral anodes 2i and 2|. interconnected by an annular ring corresponding to. that portion or wall ll between the rings 28 and 29. Such an arrangement is indicated schematically by the circuit diagram of Fig. l.

In Fig. 4 the magnetron discharge device is indicated as including a plurality of active anodes i5, 46, i?- and i8 separated into pairs by shielding means which may comprise the anodelike members 19 andv i) inter-connected by any suitable means such as those indicated schematically in cross section as an annular ring 5i corresponding for example, to that portion of the wall ll of Fig. 2- between the rings 23 and 29. A suitable evacuated enclosure is indicated schematically by the dotted line 52. Structural details of the magnetron discharge device are omitted for the purpose of simplicity of illustration since it will be understood that suitable details of construction will occur to anyone skilled in the art. They may in fact be devised by minor modifications of the structure shown in Figs. 2 and 3 or in my aforesaid co-pending application. A cathode 53 similar to that of Fig. 2 may be employed as indicated. Members 48 and 5B are shown as connected to the cathode 53 through a battery 54 in a manner similar to the arrangement in Fig. 2, it being understood that they will be connected by low impedance paths such as satisfy the condition already indicated, i. e. such that substantially no high frequency voltage exists between the cathode and the shielding means. The pair of anodes 35 and it; may be connected in electrically energizing relationship to a suitable high-Q resonant tank circuit such as the parallel wire transmission line comprising the parallel wires 55 and 56 provided with a suitable tuning short 5? which is adjustable along the length of the line. In a similar manner, the pair of anodes 41 and '58 are connected in energizing relationship to a parallel wire line employed as a load circuit. That line may comprise parallel wires 58 and 58 across which a suitable load indicated schematically by resistor-or impedance 6!] is connected at a suitable point. As in the arrangement of Fig. 2, the anodes 45 through 48 and the members is and 55- are subjected to a unidirectional positive potential with respect to the cathode by means of a battery 54 and the wire connections indicated. Any suitable means (not shown) for providing a magnetic field perpendicular to the plane of the diagram maybe provided as in the case of Figs. 2 and 3. From the foregoing discussion of Figs. 2 and 3 it will be apparent that the tank and load circuits of Fig. 4 will be relatively mutually decoupled and to, those skilled in the art that various changes and modifications may be. made without depart ing from invention in its broadest aspects,

and I, therefore, aim in the appended claims to cover all; such changes and, modifications as fall within the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. A generator of high frequency oscillations comprising in combination, a frequency determining resonant circuit, aload circuit for deriving useful energy from said generator, meansfor sustaining high frequency oscillations in said circuits comprising an electrical discharge device of; the magnetron type including a cathode and; a plurality of anodes in operative relation to a space charge chamber adapted to accommodate a rotating space charge of the magnetron type, means electricall connecting one of said anodes to said resonant circuit and means electrically connecting another of said anodes to said load circuit whereby oscillations in the said circuits may be sustained by inter-action between said space charge and said anodes, means within said device mutually shielding from each other said anodes connected; to said resonant and load circuits and means for maintaining said shield-ingmeans at substantially: zero high frequency voltage with respect to said cathode. whereby mutual coupling between said circuits through said anodes connected to said, circuits is minimized.

2. A generator ofhigh frequency oscillations comprising in combination, a high Q resonant circuit stabilizing the frequency of said generator, a load circuit for deriving useful energy from said generator, means for sustaining high frequency oscillations in said circuits comprising an electrical discharge device of the magnetron type including a cathode and a pluralit of anodes in operative relation to a space charge chamber adapted to accommodate a rotating space charge of the magnetron type, means electrically connecting a pair ofsaid anodes tosaid resonant circuit and another pair of said anodes to said load circuit whereby oscillations in the said circuits may be sustained by inter-action between said space charge and said anodes, means mutually shielding said first mentioned pair of anodes from said second mentioned pair of anodes, and means for maintaining said shielding means at substantially zero high frequency voltage with respect to said cathode whereby mutual coupling between said circuits through said pairs of anodes is minimized.

3, A generator of high frequency oscillations comprising in combination, a frequency determining resonant circuit, a load circuit for deriving useful energy from said generator, means for sustaining high frequency oscillations in said circuits comprising an electrical discharge device of the magnetron type including a cathode and a plurality of'anodes having faces defining a space charge chamber adapted to accommodate a rotating space charge of the magnetron type, means electrically connecting a pair of said anodes on one side; ofsaid chamber to said resonant circuit and means electrically connecting another pair of said anodes on the other side of said chamber to said load circuit whereby oscillations in the said circuits may be sustained by inter-action be-. tween said; space. chareeand said anodes, shield,-

'i'n'g means interposed between said'pair of anodes,

comprising in combination, an oscillatory circuit,

means for sustaining high frequency oscillations in said circuit. comprising an electrical discharge device of the magnetron typeincluding a cathode and a plurality of anodes'having juxtaposed faces defining a space charge chamber adapted to accommodate a rotating space charge of the magnetron type, means for maintaining a pair ofsaid anodes at substantially zero high frequency voltage with respect'to'said cathode, means electrically connecting each of another pair of said anodes to said circuit in electrically energizing relationship therewith whereby oscillations in said circuit may be sustain d by interaction between said space charge and said anodes, each of said first mentioned pair of anodes defining a portion of said chamber intermediate between the portions defined by said other pair of anodes and the remaining anodes of said plurality of anodes whereby mutual coupling between said other pair of anodes and the remaining anodes of said plurality of anodes is minimized.

5. A generator of high frequency oscillations comprising in combination, a frequency -deter mining resonant circuit, a load circuit for deriving useful energy from saidgenerator, means for sustaining high frequency oscillations in said circuits comprising an electrical discharge device of the magnetron type including'a cathode and a plurality of anodes having juxtaposed faces defining a space charge chamber adapted to accommodate a rotating space charge of the magnetron type, means for maintaining two of said anodes at substantially zero high frequency voltage with respect to said cathode, means electrically connecting one group of said anodes to said frequency determining circuit and means electrically connecting another group of said anodes to said load circuit whereby oscillations in said circuits may be sustained by the interaction between said space -charge and said groups of anodes, each of said first mentioned two anodes defining a portion of said chamber intermediate between the portions defined by said groups of anodes whereby mutual coupling between said circuits through said groups of anodes is minimized.

6. A generator of high frequency oscillations comprising in combination, a resonant high Q oscillatory circuit stabilizing the frequency of said generator, a load circuit for deriving useful energy from said generator, means for sustaining high frequency oscillations in said circuits comprising an electrical discharge device of the magnetron type including a cathode and. a plurality of anodes having juxtaposed faces defining a space charge chamber adapted to accommodate a rotating space charge of the magnetron type, means for maintaining two of said anodes at substantially zero high frequency voltage with respect to said cathode, means electrically connecting said load circuit to one of said two anodes and to another of said anodes, means electrically connecting said resonant circuit to one of said two anodes and to another of said anodes whereby oscillations in said circuits may be sustained by interaction between said space charge and said other anodes, each of said first mentioned two anodes defining a portion of said chamber intermediate between the portions defined by said other anodes wherebymutual coupling between said circuits through said other anodes is minimized.

7. A generator of high frequency oscillations comprising in combinatioman electron discharge device of the magnetron type including a substantially cylindrical metallic wall, a plurality of anodes within said wall having juxtaposed faces defining a space charge chamber adapted to accommodate a rotating space charge of the magnetron type, two of said anodes being insulated from said wall, two other of said anodes being conductively connected to said wall, a cathode within said chamber, a resonant frequency determining circuit for said generator comprising substantially cylindrical inner and outer concentric metallic conductors connected to one end of said wall, a load circuit for deriving "useful energy from said generator comprising substantially cylindrical inner and outer concentric metallic conductors connected to the other endof said wall, said outer conductors constituting conductive extensions of said wall and said inner conductors being connected each to one of said first mentioned anodes whereby oscillations in said circuits may be sustained'by interaction between saidspace charge and said anodes, each of said two anodes defining a portion of said chamber intermediate between the portion defined by said other anodes whereby mutual coupling between said circuits through said two anodes is minimized, and means for energizing said generator.

- comprisingin combination, an electron discharge device of the magnetron type including a substantially cylindrical metallic wall, a plurality of anodes within said wall having juxtaposed faces defining a space charge chamber adapted to accommodate a rotating space charge of the magnetron type, two of said anodes being insulated from said wall, two other of said anodes being conductively connected to said wall, a cathode within said chamber, a high Q resonant frequency determining circuit for said generator comprising substantially cylindrical inner and outer concentric metallic conductors connected to one ml of said wall and adjustable tuning means therefor, a load circuit for deriving useful energy rom said generator comprising substantially cylindrical inner and outer concentric metallic conductors connected to the other end of said wall, said outer conductors constituting conductive extensions of said wall and said inner conductors being connected each to one of said two anodes whereby oscillations in said circuits may be sustained by interaction between said space charge and said anodes, each of said first mentioned two anodes defining a portion of said chamber inter- 'mediate between the portions defined by said other anodes whereby mutual coupling between said circuits through said first mentioned two anodes is minimized, and means for energizing said generator.

9, A generator of high frequency oscillations comprising in combination, an electron discharge device of the magnetron type including an hermetically sealed envelope having a substantially cylindrical metallic wall and insulating seals sealing the ends of said wall, a plurality of anodes within said envelope having juxtaposed faces defining a space charge chamber adapted to ac- :11 bdmmodate a rotating space charge of the mag- ;netron type, two of said'anodes having externally accessible conductive connections each passing through one of said seal-s, two other of said anodes being conductively connected to said wall, 1

aa-cathode within said chamber, a resonant fre- :.quency determining circuit for said generator comprising substantially cylindrical inner and outer metallic conductors connected to one end of said wall, a load circuit for deriving useful energy from said generator comprising substantially cylindrical inner and outer concentric metallic conductors connected to the other end 10f said walLsaid outer conductors being detach- -ably;connectedito said wall and constituting conductive extensions thereof and said inner conductors bein detachably connected to said conductive connections of said first mentioned two anodes and constituting conductive extensions thereof whereby oscillations in said circuits may :be sustained by interaction between said space charge and said anodes, each of said first mentioned two anodes defining a portion of said chamber intermediate between the portions defined by said other anodes, whereby mutual coupling between said circuits through said first mentioned two anodes is minimized, and means tor energizing said generator.

-1-0. A generator of high frequency oscillations comprising in combination, an electron discharge device of the magnetron type including an hermetically sealed envelope having a substantially cylindrical metallic wall and insulatin seals sealing the ends of said wall, a plurality of anodes within said envelope having juxtaposed faces defining a space charge chamber adapted to accommodate a rotating space charge of the magnetron type, two of said anodes -having externally 12 "accessible conductive connections each passing through one of said seals, two other of said anodes being conductively mounted on said wall, a cathode withinsaid chamber, a, high Q resonant frequency determining circuit T01 said generator comprising substantially cylindrical inner and outer metallic conductors connected to one end of said wall and adjustable tuning means therefor, .a load circuit for deriving usefulenergy from said generator comprising substantially cylindrical inner and outer concentric metallic conductors connected to the other end of said Wall, said outer conductors being detachably connected to said wall and constituting conductive extensions thereof and said inner conductors being detachably-connected to said conductive connections or said first mentioned anodes and constituting conductive extensions thereof whereby oscillations in said circuits may be sustained by interaction between said space charge and said anodes, each of said first mentioned two anodes defining a portion of said chamber intermediate between the portions defined by said other anodes, whereby mutual coupling between said circuits through said first mentioned two anodes is minimized, and means for energizing said generator.

RICHARD B. NELSON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name :Date

2,112,822 Braden Apr. 5, 1938 2,168,296 DeVries vet al. Aug. 1, 1939 

